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RT @f1tenth: Say hi to our newest #F1TENTH creation for @ieee_ras_icra next week in Philly. It’s going to be huge! 😎 🔥 @AutowareFdn @PennEn…
Our next Virtual Race will be on June 4th:
https://www.meetup.com/DIYRobocars/events/285787423?utm_medium=referral&utm_campaign=share-btn_savedevents_share_modal&utm_source=link
RT @SmallpixelCar: Noticed my car zigzagged in last run. It turned out to be the grass stuck in the wheel and made the odometry less accura…
RT @SmallpixelCar: Test my car. RTK GPS worked great. Thanks @emlid for their support. https://t.co/EkQ6qmjmWR
RT @chr1sa: @kane That's @diydrones circa 2009. Still have a box of those Canon cameras that we used to strap into planes, just like this.…
RT @chr1sa: Our next @diyrobocars race is going to be outside at a real RC racetrack in Fremont on May 28. Fully autonomous racing, head-to…
RT @f1tenth: Our Spring 2022 F1TENTH course @PennEngineers is coming to an end with a head-to-head race as a big finale. So proud of our st…
RT @DanielChiaJH: I wrote a thing! Throughout the development of my @diyrobocars car I've been using @foxglovedev Studio to visualize and d…
RT @SmallpixelCar: My new car for high speed. Low body, everything ( @NVIDIAEmbedded Jetson Xavier NX, @emlid RTK GPS, IMC) under the deck…
RT @f1tenth: F1TENTH Race training setup @PennEngineers for our upcoming ICRA2022 @ieee_ras_icra competition. @OpenRoboticsOrg @IndyAChalle…
RT @fatcatFABLAB: Proud to be hosting a restarted DIY Robocars NYC Meetup April 26. Come by if you want to talk about and race self-driving…
Replies
A resolution of 0.1 knot is impressive Marc. Can you describe the specialized code you use to pull the signal from the noise?
Jeff, did you notice this thread is nearly 6 years old?
By "specialized" I meant specific to the implementation of a variometer. In our case, using the microcontroller onboard ADCs and digital filters, combined with simple linear boxcar filtering in the code was good enough to achieve that level of resolution on a desktop. In a glider we use the variometer in conjunction with a total energy compensator, which mixes altitude with airspeed to calculate total energy altitude, either before the variometer pressure sensor sees it (using a pneumatic compensating probe), or in the variometer code (using airspeed sensor data). When in turbulent air, a glider encounters horizontal gusts, causing transient fluctuations in airspeed which, in turn, show up as (sometimes large) fluctuations in variometer reading. This was addressed by implementing a "gust filter" as the final step in the variometer code. We tried a variety of filter implementations, but simply rate limiting the change in variometer indication was sufficient to damp down the transients, while not interfering with the all important task of finding rising air.
I've able to measure vertical speed down to a resolution of less than 0.1 knot (5 cm/sec) using an absolute pressure sensor, 24 bit A/D converter (needs about 18 to 19 bits effective resolution), and digital differentiation, but it takes a lot of specialized code to separate the signal from the noise...